1. Field of the Invention
The present invention relates to a slat angle adjusting device, and more particularly to a slat angle adjusting device for a Venetian blind.
2. Description of Related Art
The closest prior art of which the applicant is aware is disclosed in the applicant""s U.S. Pat. No. 5,680,892, filed on Jul. 31, 1996, entitled xe2x80x9cSLAT ANGLE ADJUSTING DEVICE FOR VENETIAN BLINDxe2x80x9d. With reference to FIG. 4, the conventional slat angle adjusting device for a Venetian blind referred to in the ""892 patent comprises a body (50), and a roller (54). The body (50) is securely positioned to the headrail (70) of the Venetian blind for the tilt rod (72) extending through the body (50). A transmission device (not shown) is arranged in the body (50) and is connected to the tilt rod (72). The roller (54) is rotatably attached to the body (50) and is operationally connected to the transmission device. A cord (60) is wound around the,roller (54) and extends through a base (56) and the headrail (70). When the user pulls the cord (60), the tilt rod (72) will rotate through the transmissions of the roller (54) and the transmission device. Consequently, the angle of the slats of the Venetian blind will be adjusted.
A positioning bar (52) is formed on the top of the body (50) to securely position the body (50) to the headrail (70). Two C-shaped forked ends (522) are formed on the opposite ends of the positioning bar (52) to engage two upper bent portions of the headrail (70). Each forked end (522) has an upper tongue (524) abutting the top of the bent portion of the headrail (70) and a lower tongue (526) abutting the bottom of the bent portion of the headrail (70).
However, because the length of the lower tongue (526) of the forked end (522) on the positioning bar (52) of the conventional adjusting device is substantially equal to that of the upper tongue (526), to assemble the body (50) to the headrail (70) with the positioning bar (52) is difficult. In addition, a notch (542) is defined in each respective side of the roller (54) to engage a knot (not numbered) formed on the cord (60), such that the cord (60) can be securely held onto the roller (54). Nevertheless, the positioning effect between the notch (542) and the knot on the cord (60) is not enough for common use, and there is no structure on the roller (54) of the conventional adjusting device to provide a further positioning effect to the cord (60). When the user pulls the cord (60) with a large force, the knot can release from the notch (54).
To overcome the shortcomings, the present invention tends to provide a slat angle adjusting device to mitigate or obviate the aforementioned problems.
The main objective of the invention is to provide a slat angle adjusting device for a Venetian blind and that is easy to assemble to the headrail. The slat angle adjusting device has a body, a roller, a transmission device and a positioning bar. The roller is rotatably attached to the body for a cord being wound around the roller. The transmission device is received in the body and operationally connected to the roller. The positioning bar is integrally formed on the top of the body and has two forked ends adapted to engage with upper bent portions of a headrail of the Venetian blind. Each forked end has an upper tongue and a lower tongue respectively adapted for abutting the top and the bottom of the bent portion on the headrail. The lower tongue has a length shorter than a half of the length of the upper tongue. Accordingly, to assemble the body to the headrail with the positioning bar is easy due to the length arrangement of the lower tongue.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.